1. Field of the Invention
The present invention relates to a tilt device for a marine propulsion unit.
2. Description of the Related Art
In the prior art, as described in Japanese Utility Model Registration No.2520691, there is a tilt device for a marine propulsion unit comprising a boat body, a marine propulsion unit tiltably supported on the boat body, and a cylinder device interposed between the boat body and the marine propulsion unit, and in which a hydraulic fluid is controlled to be supplied or discharged from or into a hydraulic fluid supply/discharge device into or from the cylinder device, thereby expanding or contracting the cylinder device so that the marine propulsion unit is tilted. In this prior art, the hydraulic fluid supply/discharge device comprises a motor, a pump, a tank and a passage having a switch valve. The tank and the passage having the switch valve are molded in a valve block, the pump is disposed in a pump chamber provided in the valve block, and the motor is mounted on the pump.
However, the prior art has the following disadvantages.
(1) In addition to the passage having the switch valve and the pump incorporated in the valve block constituting the hydraulic fluid supply/discharge device, a separate tank is provided. Therefore, the hydraulic fluid supply/discharge device must be enlarged in size, and a space occupied by the hydraulic fluid supply/discharge device around the marine propulsion unit is excessively increased.
(2) Since a yoke (outer cylinder) of the motor of the hydraulic fluid supply/discharge device utilizes an electromagnetic force, the yoke is made of iron. However, since the yoke is exposed to the outside, it is necessary that the yoke is subjected to a surface anti-corrosion treatment.